Some weeks ago I asked here if anyone knew what was going on with my hot
water supply essentially drying up after a few minutes when running a bath.

Well it wasnt such a big deal as mostly I shower, but today whilst
shaving after a shower the hot tap basically stopped altogether.

Cold tap worked fine, so it had to be something in the HE circuit

This prompted me to take up the matter again and lo! the internet is
FULL of stories about pressurised cylinders where the input pressure
regulator fails in some way.

I didn't even know these things HAD a pressure regulator!

It appears that the cold feed comes in via a preset 2.1 bar regulator
and filter assembly and thats what the tank should run at. There is an
air bubble in the top that is the 'pressure vessel' and an 8 bar
'overpressure' dump into the tundish. If something goes wrong with the
air bubble.

If flow is restricted the pressure will be there and as long as the air
bubble does its job, it will be 2.1 bar slowly falling until expansion
is complete then sweet fanny adams. I think that this probly means that
the pressure valve is doing its pressure thing, but the input filter is
so clogged with scale it can't handle replenishing water at the rate needed.

Which raises the question as to whether the water softener is in fact
working properly.

I did have root around inside the salt bit to see if that was OK, and
found a drowned mouse....what!!!!???? yes. A drowned mouse.!

This also would explain why I have been getting air in the hot water
taps. The bubble has expanded so MUCH that some of its air is getting
into the hot water outlet which is near the tank top...

Anyway although a qualified plumber is supposed to do this, I have
ordered a replacement regulator which, after switching off the leccy to
the immersion and CH system, turning off the inflow to the tank and
draining down the tank (open the lowest hot tap in the house and push
the tundish test thing to let air in: also will remake the 'bubble'),
should be unscrew and refit, corrosion permitting...

Wish me luck..




--
Karl Marx said religion is the opium of the people.
But Marxism is the crack cocaine.

I suppose I should know as I have an unvented cylinder "installers" CITB certificate but I'm not sure maintenance demands the same bit of paper. As long as renewal with like for like is involved and you dont compromise safety critical components what's the problem?
No one in officialdom will know unless you tell them.
Most of the unvented cylinders I've met have a diaphragm type "cushion" vessel but the principle is the same. I'd be looking for a restriction on the input as first port of call.

On 06/02/2019 16:38, The Natural Philosopher wrote:

Some weeks ago I asked here if anyone knew what was going on with my hot
water supply essentially drying up after a few minutes when running a bath.

Well it wasnt such a big deal as mostly I shower, but today whilst
shaving after a shower the hot tap basically stopped altogether.

Cold tap worked fine, so it had to be something in the HE circuit

This prompted me to take up the matter again and lo! the internet is
FULL of stories about pressurised cylinders where the input pressure
regulator fails in some way.

I didn't even know these things HAD a pressure regulator!

It appears that the cold feed comes in via a preset 2.1 bar regulator
and filter assembly and thats what the tank should run at. There is an
air bubble in the top that is the 'pressure vessel' and an 8 bar
'overpressure' dump into the tundish. If something goes wrong with the
air bubble.

If flow is restricted the pressure will be there and as long as the air
bubble does its job, it will be 2.1 bar slowly falling until expansion
is complete then sweet fanny adams. I think that this probly means that
the pressure valve is doing its pressure thing, but the input filter is
so clogged with scale it can't handle replenishing water at the rate
needed.

Which raises the question as to whether the water softener is in fact
working properly.

I did have root around inside the salt bit to see if that was OK, and
found a drowned mouse....what!!!!???? yes. A drowned mouse.!

This also would explain why I have been getting air in the hot water
taps. The bubble has expanded so MUCH that some of its air is getting
into the hot water outlet which is near the tank top...

Anyway although a qualified plumber is supposed to do this, I have
ordered a replacement regulator which, after switching off the leccy to
the immersion and CH system, turning off the inflow to the tank and
draining down the tank (open the lowest hot tap in the house and push
the tundish test thing to let air in: also will remake the 'bubble'),
should be unscrew and refit, corrosion permitting...

Wish me luck..




Well to all those who didn't wish me luck, I didn't need it. I did
however find the old manifold impossible to take apart so refitted a new
complete assembly.

That didn't quite fit either - it came in two halves screwed together
with a weird plastic washer inserted in a groove in the male thread
that simply wouldn't allow it to be screwed up tight. In the end I cut
that out and fitted the two halves with PTFE tape.

Still too long but there was enough wiggle in the pipework to fit it all.

Instant proper hot water flow.

So the knock on effects of not getting the pressure vessel replaced were
two gland leaks that knocked out the electrics and needed a new gate
valve, a new ball valve, and a new motorised valve.

And the knock on effects of not using the water softener were completely
clogged/seized hot water inlet regulator/filter assembly to the HW tank.

No hot water.

I hope that is the end of the plumbing problems, but I wouldnt mind
betting there are a few more. Cold mains pressure seems a little low.
And not 100% sure the softener is working though it feels like it when
soaping hands...









--
"When one man dies it's a tragedy. When thousands die it's statistics."

Josef Stalin

On Mon, 11 Feb 2019 11:56:25 +0000, The Natural Philosopher wrote:

And not 100% sure the softener is working though it feels like it when
soaping hands...

Can you get some water before it's gone through the softner? And
compare with water that has. Hard water and soap (proper bar soap
not a detergent hand wash) will be reluctant to lather up and will
tend form a scum in hard water.

--
Cheers
Dave.

On 11/02/2019 23:35, Dave Liquorice wrote:
On Mon, 11 Feb 2019 11:56:25 +0000, The Natural Philosopher wrote:

And not 100% sure the softener is working though it feels like it when
soaping hands...

Can you get some water before it's gone through the softner? And
compare with water that has. Hard water and soap (proper bar soap
not a detergent hand wash) will be reluctant to lather up and will
tend form a scum in hard water.

yeah. I have one inside and one outside tap that are unsoftened.

I managed to feel behind the unit, and the bypass is closed allright, so
water miust be going through it,

It IS using salt, but at about 1/5th the level it used to.


--
"The great thing about Glasgow is that if there's a nuclear attack it'll
look exactly the same afterwards."

Billy Connolly